Light-to-digital sensors simplify smart brightness control

Milpitas, Calif.—Intersil's ISL29001 and ISL29002 sensors convert visible light (380 to 770 nm) to a 15-bit, I2C output signal suited to smart display applications. "These devices are fully integrated to give customers a one-chip solution that converts light intensity to a 15-bit, I2C digital output signal that can be fed directly into a controller for backlight control in portable applications," said Oleg Steciw, marketing manager for the Display products group. These applications include flat-panel and keyboard backlight control, medical and industrial sensing, digital and still cameras, and intrusion detection.

The devices, powered from a 2.5- to 3.3-volt source, integrate a current amplifier, 50-60 Hz rejection filter to eliminate artificial light flicker, and a 15-bit ADC. These sensors achieve peak sensitivity close to that of the human eye, according to the company; the chip's low power consumption will extend battery life and panel visibility in backlight control applications.
The ISL29001 accommodates 0.3 lux to 10,000 lux inputs and the ISL29002's range is from 1.0 lux to 100,000 lux. These devices automatically compensate for die temperature by utilizing a proprietary two-diode design. Resolution is adjustable from 3 to 15 counts per lux on the ISL29001; 0.15 to 1.65 counts per lux on the ISL29002. The output code is directly proportional to the illumination.

The chips also feature three address-selection pins that allow up to eight sensors on a single I2C bus line. These devices also include a power-down mode for further power savings.

Click here for additional information on the ISL29001 and here for the ISL29002. The ISL29001, in a 2-by-2.1 mm lead-free DFN package and rated for operation over -40 to +85&degC, and the ISL29002 (3-by-3 mm package DFN, rated for 0 to +70&degC operation, are priced at $1.30 and $1.39 each, respectively, in 1k quantities.

Click here to visit the company's Display ICs page. A large selection of amplifier products is supported by Intersil's iSim online design tool. To explore these solutions, click here. To view a broad range of application block diagrams, click here.